The solar system and time

Question 1

Aphelion is the point during orbit around the sun where -

Answer 1

the earth is farthest from the sun

Question 2

Perihelion is the point during orbit around the sun where -

Answer 2

the earth is closest to the sun

Question 3

Aphelion occurs approximately in -

Answer 3

July 4th

Question 4

Perihelion occurs approximately in -

Answer 4

January 4th

Question 5

The change of seasons is due to?

Answer 5

The inclination(tilt) of the earth

Question 6

The earth’s spin axis(approximately N/S, in reference to the orbital plane around the sun, is tilted at an angle of -

Answer 6

66.5 degrees.

Question 7

In the NH winter solstice occurs -

Answer 7

on 21st of December

Question 8

In the SH winter solstice occurs -

Answer 8

on 21st of June

Question 9

In the NH summer solstice occurs -

Answer 9

on 21st of June

Question 10

In the SH summer solstice occurs on -

Answer 10

21st of December

Question 11

In the SH autumn equinox occurs on -

Answer 11

March 21st

Question 12

In the NH spring equinox occurs on -

Answer 12

March 21st

Question 13

In the SH spring equinox occurs on -

Answer 13

September 21st

Question 14

In the NH autumn equinox occurs on -

Answer 14

September 21st

Question 15

If the North Pole is tilted at its maximum possible angle towards the sun, which hemisphere will experience winter?

Answer 15

Southern Hemisphere

Question 16

If the North Pole is tilted at its maximum possible angle away from the sun, which hemisphere will experience winter?

Answer 16

Northern Hemisphere

Question 17

The apparent solar day is of -

Answer 17

variable length and not suitable for time keeping

Question 18

An apparent solar day is always longer than -

Answer 18

a sidereal day

Question 19

The mean solar day(exactly 24 hours) is used as the -

Answer 19

basis for time keeping

Question 20

The type of “day” definition that is not constant?

Answer 20

An apparent day

Question 21

1 hour of a mean solar day = how many degrees?

Answer 21

15 degrees

Question 22

LMT(local mean time) is the same for a given meridian irrespective of -

Answer 22

latitude

Question 23

To convert LMT to UTC/Zulu/GMT time, the mnemonic is?

Answer 23

Longitude East, UTC least

Longitude West, UTC best

Question 24

UTC =

Answer 24

GMT

Question 25

GMT =

Answer 25

UTC

Question 26

AM and PM means -

Answer 26

Ante-meridian and post meridian

Question 27

AM and PM:

Morning will be during =

Answer 27

Ante-meridian

Question 28

AM and PM:

Afternoon will be during =

Answer 28

Post-meridian

Question 29

UTC is 13:23:00, determine the standard time at Durban(30 degrees 57 minutes east). The STF is 2

Answer 29

The STF is either added or subtracted to/from UTC in order to find the standard time. No need to find the arc time.

East UTC least

West UTC best.

Question 30

Define standard time -

Answer 30

Standard time is a further development of zone time to allow a country to adopt one time as its standard. South Africa is in fact a case in point. Most of the republic falls into the zone which is UTC + 2 hours, but some parts - notably cape town - are on zone UTC + 1 hour. To make life simple, south africa has adopted UTC + 2 hours for the whole country. This will be expressed as Standard Time Factor of 2. To determine whether to add or subtract the STF, the longitude of the position in relation to the Greenwich meridian must be known.

always remember: East UTC least. West UTC best

Question 31

The international date line is =

Answer 31

The Ante-meridian(180E/W)

Question 32

Local mean time noon will occur -

Local mean time sunset and sunrise will occur -

Answer 32

at 12:00, on any latitude for the same meridian.

at the same time only for the same meridian and on the same parallel.

Question 33

LMT is relative to the -

Answer 33

local meridian.

Question 34

LMT between 30°00’ E and 60°00’ E will differ by -

Answer 34

360/24 = 15° per hour.

30°(long difference) / 15° = 2 hours.

The local mean time will differ by 2 hours.

Question 35

LMT at A 30°00’ W = 13:00. What is the LMT at B 20°00’ W?

Answer 35

This problem can be solved by only using arc time and a little logic to figure which time is before which, but using this method for more complex problems is not easier. Convert to UTC.

Since A is to the west of UTC, we need to add to the LMT(west UTC best):

30° / 15° = 2 hours.

13:00 + 2 = 15:00 UTC

B is also to the west:

20° / 15 = 1:20m.

Since we already have a UTC of 15:00, we need to reverse the west best/east least mnemonic.

15:00 - 1:20 = 13:40 LMT.

LMT at B = 13:40.